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Preliminary
RT9182
Dual, Low-Noise, 200mA LDO Regulator
General Description
The RT9182 is a dual-channel, low noise, and low dropout regulator supplying up to 200mA current at each channel. The output voltage ranges from 1.5V to 3.3V in 100mV increments and 2% accuracy by operating from a +2.7V to +6.5V input. The RT9182 uses an internal PMOS as the pass device, which consumes 165A supply current (both LDOs on) independent of load current and dropout conditions. The SHDN pin controls both outputs simultaneously and consumes nearly zero operation current in the disable mode making the IC suitable for battery-power devices. Other features include a reference voltage bypass pin to improve low noise performance, current limiting, and over temperature protection.
Features
* Up to 200mA Output Current (Each LDO) * Shutdown Function * 29VRMS Low Noise Output * Current Limiting and Thermal Protection * Short Circuit Protection * 120mV Dropout at 100mA Load * Two LDOs in SOT-26 Package
Applications
Cellular Phones Laptop, Notebook, and Palmtop Computers Battery-powered Equipment Hand-held Equipment
Pin Configurations
Part Number RT9182 CE (Plastic SOT-26)
6 5 4
Pin Configurations
TOP VIEW 1. 2. 3. 4. 5. 6. VOUT2 GND BP SHDN VIN VOUT1
Ordering Information
RT9182 Package type E : SOT-26 Operating temperature range C : Commercial standard Output voltage A : 2.8V (Output1), 2.8V (Output2) B : 3.0V (Output1), 3.0V (Output2)
1
2
3
Typical Application Circuit
ON OFF VOUT2 2.2F BP GND 10nF SHDN VOUT2 VOUT1 VOUT1 2.2F VIN 2.2F
Marking Information
Part Number RT9182ACE RT9182BCE Marking 2M 2Q
RT9182
VIN
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RT9182
Pin Description
Pin Name VOUT2 GND BP SHDN VIN VOUT1 Pin Function Output2 Voltage Ground Reference Noise Bypass Active Low Shutdown Input Power Input Output1 Voltage
Preliminary
Function Block Diagram
VIN
Current Limit
Thermal Protection
Current Limit
+
VOUT1
Bias BP Start-Up
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2
_
_
Vref
+
VOUT2
GND SHDN
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Preliminary Absolute Maximum Ratings
Input Voltage Power Dissipation, PD @ TA = 25C SOT-26 Junction Temperature Range Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering, 10 sec.)
RT9182
7V 748mW -40C ~ 125C -65C ~ 150C -40C ~ 85C 260C
Electrical Characteristics
(VIN = 3.6V, CIN = COUT = 2.2F, SHDN = VIN, typical values at TA = 25C, for each LDO unless otherwise specified.) Parameter Input Voltage Range Output Voltage Accuracy (Load Regulation) Maximum Output Current Current Limit GND Pin Current Symbol VIN VOUT IMAX ILIMIT IG IL = 1mA to 200mA Continuous RLOAD = 1 No Load IOUT = 100mA (Both LDOs) IOUT = 1mA Dropout Voltage
(Note)
Test Conditions
Min 2.7 -2 200 200 ------0.2 1.6 ------
Typ ----165 165 1.2 120 255 ----0.01 140 10 29 62
Max 6.5 +2 -550 260 260 ---+0.2 -0.4 100 1 -----
Units V % mA mA A A mV mV mV %/V V V nA A C C VRMS dB
VDROP
IOUT = 100mA IOUT = 200mA VIN = (VOUT +0.4V or 2.7V) to 6.5V IOUT = 1mA VIN = 2.7V to 6.5V VIN = 2.7V to 6.5V SHDN = GND or VIN SHDN = GND
Line Regulation SHDN Input High Threshold SHDN Input Low Threshold SHDN Input Bias Current Shutdown Supply Current Thermal Shutdown Temperature Thermal Shutdown Hysteresis Output Voltage Noise Output Voltage AC PSRR
VLINE VIH VIL ISD IGSD TSD eNO
10Hz to 100kHz, CBP = 10nF COUT = 4.7F, ILOAD = 1mA 100Hz, CBP = 10nF, COUT = 4.7F ILOAD = 100mA
---
Note : Dropout voltage definition: VIN - VOUT when VOUT is 50mV below the value of VOUT (normal)
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RT9182
Preliminary
Typical Operating Characteristics
VOUT = 2.8V, ILOAD = 100mA, VIN = 3.6V, COUT = 4.7F, CBP = 10nF, and CIN = 2.2F, unless otherwise noted.
Quiescent Current vs. Supply Voltage
240 200 1.0 0.8
Output Voltage Accuracy vs. Temp.
Quiescent Current ( A)
No Load ILoad = 100mA, both outputs
0.6
Output Voltage (%)
160 120 80 40 0 2.5 3.5
0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0
4.5
5.5
6.5
-40
-15
10
35
60
85
Supply Voltage (V)
Temperature ( C)
Quiescent Current vs. Load Current
180
Dropout Voltage vs. Temp.
300 250
Both outputs loaded
150
Quiescent Current ( A)
Dropout Voltage (mV)
120 90 60 30 0 0 40 80 120 160 200
200 150 100 50 0 -40 -15 10 35
ILOAD = 200mA
60 85
Load Current (mA)
Temperature ( C)
Quiescent Current vs. Temp.
200 175
70 60 50
PSRR vs. Frequency
ILOAD = 1mA
Quiescent Current ( A)
150
PSRR (dB)
125 100 75 50 25 0 -40 -15 10 35 60 85
40 30 20 10 0
10
100
1K
10K
100K
1M
Temperature ( C) www.richtek-ic.com.tw
Frequency (Hz) DS9182-02 April 2002
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Preliminary
Channel-to-Channel Isolation vs. Frequency
10K
RT9182
Noise Density vs. Frequency
120 100
Noise Density (nV/ Hz )
RLOAD = 100 100 1K
Channel Isolation (dB)
80 60 40 20 0
1K
100
Frequency (Hz)
10K
100K
1M
10 10
100
1K
10K
100K
Frequency (Hz)
Output Voltage Deviation (AC-Coupled)
T
Output Voltage Deviation (AC-Coupled)
Line Transient Response
20mV/Div
Load Transient Response (ILOAD = 0 to 80mA)
1>
50mV/Div
T
1>
Input Voltage (V)
4.5 3.5
2
T T
Load Current
100mA/Div
2>
Peak value depends on COUT ESR
T T
50S/Div Time
10S/Div Time
COUT = 2.2F
Shutdown Response
Output Voltage
Output Noise (10Hz to 100kHz)
ILOAD = 1mA
Output Voltage (AC-Coupled)
ILOAD = 50mA
1V/Div
100V/Div
T
1>
T
Shutdown Voltage
T T
1>
5V/Div
2>
1mS/Div Time
1mS/Div Time
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RT9182
Functional Description
Preliminary
The RT9182 is integrated with two low noise, low dropout, and low quiescent current linear regulators designed primarily for battery-powered applications. Output voltages are optional ranging from 1.5V to 3.3V, and each channel can supply current up to 200mA. Shutdown The RT9182 is shutdown by pulling the SHDN input low, and turned on by driving the input high. If this feature is not to be used, the SHDN input should be tied to VIN to keep the regulator on at all times (the SHDN input must not be left floating). Internal P-Channel Pass Transistor The RT9182 features double typical 1.5 P-channel MOSFET pass transistors. It provides several advantages over similar designs using PNP pass transistors, including longer battery life. The Pchannel MOSFET requires no base drive, which reduces quiescent current considerably. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive currents under large loads. The RT9182 does not suffer from these problems and consume only 165A of quiescent current whether in dropout, light-load, or heavy-load applications. Current Limit and Thermal Protection The RT9182 includes two independent current limit structure which monitor and control each pass transistor's gate voltage limiting the guaranteed maximum output current to 200mA minimum. Thermal-overload protection limits total power
event of fault conditions. Do not exceed the absolute maximum junction-temperature rating of TJ = +150C for continuous operation. The output can be shorted to ground for an indefinite amount of time without damaging the part by cooperation of current limit and thermal protection. Operating Region and Power Dissipation The maximum power dissipation of RT9182 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation across the device is P = IOUT (VIN - VOUT). The maximum power dissipation is: PMAX = (TJ - TA) / JA where TJ - TA is the temperature difference between the RT9182 die junction and the surrounding environment, JA is the thermal resistance from the junction to the surrounding environment. The GND pin of the RT9182 performs the dual function of providing an electrical connection to ground and channeling heat away. Connect the GND pin to ground using a large pad or ground plane. Low-Noise Operation An external 10nF bypass capacitor at BP, in conjunction with an internal resistor, creates a lowpass filter. The RT9182 exhibits 29VRMS of output voltage noise with CBP = 10nF and COUT = 2.2F.
dissipation in the RT9182. When the junction temperature exceeds TJ = +140C, the thermal sensor signals the shutdown logic turning off the pass transistor and allowing the IC to cool. The thermal sensor will turn the pass transistor on again after the IC's junction temperature cools by 10C, resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overloaded protection is designed to protect the RT9182 in the
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Preliminary Applications Information
Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9182 must be carefully selected for regulator stability and performance. Using a capacitor whose value is > 1F on the RT9182 input and the amount of capacitance can be located a distance of not more than 0.5" from the input pin of the IC and returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor. The capacitor with larger value and lower ESR (equivalent series resistance) provides better PSRR and line-transient response. The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all LDO applications (see Fig.1). The RT9182 is designed specifically to work with low ESR ceramic output capacitor in space-saving and performance consideration. Using a ceramic capacitor whose value is at least 1F with ESR is > 5m on the RT9182 output ensures stability. The RT9182 still works well with output capacitor of other types due to the wide stable ESR range. Output capacitor of larger capacitance can reduce noise and improve loadtransient response, stability, and PSRR. The output capacitor should be located not more than 0.5" from the VOUT pin of the RT9182 and returned to a clean analog ground. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It may be necessary to use 2.2F or more to ensure stability at temperatures below -10C in this case. Also, tantalum capacitors, 2.2F or more may be needed to maintain capacitance and ESR in the stable region for strict application environment. Tantalum capacitors maybe suffer failure due to surge current when it is connected to a lowimpedance source of power (like a battery or very large capacitor). If a tantalum capacitor is used at the input, it must be guaranteed to have a surge current
DS9182-02 April 2002
0.01 10
RT9182
sufficient for the application by the
rating
manufacture.
Region of Stable COUT ESR vs. Load Current
100
COUT = 4.7F COUT = 1F
COUT ESR (m) ()
increased without limit. The input capacitor must be
1
0.1
0.001 0 40 80 120 160 200
Load Current (mA)
Fig. 1 Use a 10nF bypass capacitor at BP pin for low output voltage noise. The capacitor, in conjunction with an internal resistor, which connects bypass pin and the band-gap reference, creates a low-pass filter for noise reduction. Increasing the capacitance will slightly decrease the output noise, and it is almost independent of the start-up time. The capacitor connected to the bypass pin for noise reduction must have very low leakage. This capacitor leakage current causes the output voltage to decline by a proportional amount to the current. Load-Transient Considerations The RT9182 load-transient response graphs show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. The DC shift is quite small due to the excellent load regulation of the IC. Typical output voltage transient spike for a step change in the load current from 0mA to 50mA is tens mV, depending on the ESR of the output capacitor. Increasing the output capacitor's value and decreasing the ESR attenuates the overshoot.
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RT9182
Input-Output (Dropout) Voltage A regulator's minimum input-output
Preliminary
voltage
differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the RT9182 uses a P-channel MOSFET pass transistor, the dropout voltage is a function of drain-to-source on-resistance [RDS(ON)] multiplied by the load current. Reverse Current Path The power transistor used in the RT9182 has an inherent diode connected between each regulator input and output (see Fig.2). If the output is forced above the input by more than a diode-drop, this diode will become forward biased and current will flow from the VOUT terminal to VIN. This diode will also be turned on by abruptly stepping the input voltage to a value below the output voltage. To prevent regulator mis-operation, a Schottky diode could be used in the applications where input/output voltage conditions can cause the internal diode to be turned on (see Fig.3). As shown, the Schottky diode is connected in parallel with the internal parasitic diode and prevents it from being turned on by limiting the voltage drop across it to about 0.3V < 100mA to prevent damage to the part.
VIN
VOUT
Fig. 2
VIN
VOUT
Fig. 3
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Preliminary Package Information
RT9182
D
C
B
b
A e A1 L
H
Symbol A A1 B b C D e H L
Dimensions In Millimeters Min 0.889 -1.397 0.356 2.591 2.692 0.838 0.102 0.356 Max 1.295 0.152 1.803 0.559 2.997 3.099 1.041 0.254 0.610
Dimensions In Inches Min 0.035 -0.055 0.014 0.102 0.106 0.033 0.004 0.014 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024
SOT- 26 Surface Mount Package
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RT9182
Preliminary
RICHTEK TECHNOLOGY CORP.
Headquarter
6F, No. 35, Hsintai Road, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5510047 Fax: (8863)5537749
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing)
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465
Email: marketing@richtek-ic.com.tw
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